The Nature of Things

Presidential Address

given to the British Society for the Philosophy of Science

by

J.R. Lucas

on June 7th, 1993

It would be improper for a President to play safe.
After two years of curbing my tongue and not making all sorts of
observations that have sprung to my mind,
in order to let you have an opportunity of having your say,
I am now off the leash.
And whereas mostly in academic life it is appropriate to adopt a prudential strategy,
and not say anything that might be wrong,
I owe it to you on this occasion to play a maximax strategy,
to speak out and say what I really think,
being willing to run the risk of being wrong in order not to forgo
the chance of actually being right in an area of the philosophy of
science which must, I think for ever,
be largely a matter of metaphysical speculation.

I stand before you a failed materialist.
Like Lucretius, from whom I have borrowed my title,
I should have liked to be able to explain the nature of things in
terms of ultimate thing-like entities of which everything was made,
and in terms of which all phenomena could be explained.
I have always been a would-be materialist.
I remember, when I was six, telling my brother, who was only two,
in the corner of a garden in Guildford,
that everything was made of electricity and
believing that electrons were hard knobbly sparks,
and later pondering whether position was a sort of quality,
and deciding that it was, absolutely considered,
but that relative positions, that is to say patterns,
as seen in the constellations in the sky,
were only in the eye of the beholder.
I am still impelled to a very thing-like view of reality,
and would like to explain electricity in terms of whirring wheels,
and subatomic entities as absolutely indivisible point-particles,
each always remaining its individual self,
and possessed of all the qualities that really signified.
I find it painful to be dragged into the twentieth century,
and though my rational self is forced to acknowledge that
things aren't what they used to be,
I find it hard to come to terms with their not being what I
instinctively feel they have got to be,
and am still liable to scream that that the world-view we are
being forced to adopt cannot be true,
and that somehow it must be fitted back into the Procrustean bed of our inherited prejudices.

But I am not going to ask you to listen to my screams.
Rather, I shall share with you my attempts to overcome them,
and work out new categories for thinking about the nature of the world,
and a correspondingly less rigid paradigm of possible explanation.
It has taken me in two different directions.
On the one hand reality is much softer and squodgier than I used to think.
It is not only that the knobbliness is less impenetrable,
as quantum tunnelling takes over,
nor that it is fuzzier, without the sharp outlines of yestercentury,
but, more difficult to comprehend, the very concept of haecceitas,
as Duns Scotus called it, this-i-ness,
or transcendental individuality,
in Michael Redhead's terminology,1
has disappeared from the categories of ultimate reality.
On the other hand, reason has become much wider and more
hospitable to new insights from various disciplines.
The two changes are connected.
Our concept of a thing, in order to be more truly a thing,
has been developed into that of a substance,
and substances have come to need to have more and more perfections,
and we have therefore come to identify as substances more
sophisticated combinations of more recherché features;
and with this change in what we regard as a thing has come also
a corresponding change in our canons of explanation.
It will be my chief aim this evening to show how our changed
apprehension of reality has opened up new vistas of rationality,
and how the wider concept of rationality we have been led to
adopt has in turn altered our view of what constitute real substances.

The corpuscularian philosophy posited the ultimate constituents of
the universe as qualitatively identical but numerically distinct,
possessing only the properties of spatial position and its time-derivatives,
and developing according to some deterministic law.
In the beginning, on this view, God created atoms and the void.
The atoms, or corpuscles, or point-particles,
were thing-like entities persisting over time,
each for ever distinct from every other one,
each always remaining the same,
each capable of changing its position in space while retaining its individual identity.
Spatial position constituted the changeable parameter which
explained change without altering the corpuscle's own identity.
Space was the realm of mostly unactualised possibility,
of changes that might, but mostly did not, occur.
But space also performed the logical function of both
distinguishing between qualitatively identical corpuscles---two
thing-like entities cannot be in the same place at the same
time---and providing,
in spatio-temporal continuity, a criterion of identity over time.
It was thus possible for each point-particle to be like every other one,
but to be a different particular individual,
and this particularity affected the corpuscularians' ideal of explanation,
articulated by Laplace, and much refined in our own time by Hempel.
Scientists seek generality, and eschew the contingent and the coincidental.
In the Hempelian paradigm, the focus of interest is on the covering law,
which is general, and not on the initial conditions,
which just happen to be what they are,
and can only themselves be explained by the way earlier states of
the universe happened to be.
Boundary conditions,
being the particular positions and velocities of particular point-particles,
are too particular to constitute the sort of causes that scientists,
in their search for generality,
are willing to take seriously as genuinely explanatory.

The corpuscularian philosophy had many merits.
It reflected our experience of things:
stable objects that persist over time,
clearly individuated by exclusive space-occupancy,
capable of change without losing their identity.
As a metaphysical system it had great economy and power.
All macroscopic things, all events and phenomena,
were to be explained in terms of the positions and movements of these ultimate entities.
There was a clear ontology, a clear canon of explanation,
and a clear demarcation between physically necessary laws and
purely contingent initial conditions.
Of course, there were also grave demerits.
From my own point of view---though I have failed to persuade
Robin Le Poidevin of this2---time is essentially tensed,
and it counts against the corpuscularian scheme that it did not
account for the direction of time or the uniqueness of the present:
more influential in the history of science was the account of space,
and the difficulty in formulating a plausible account of how
corpuscles could interact with one another,
which in due course led us to replace corpuscularian by field theories,
as being better able to account for the propagation of causal influence.
The vacuum,
though adequate for giving things room to exist and move in,
was too thin to let them interact with one another,
and Voltaire has had to return from London to Paris.

But it was not only space that proved too thin to do its job.
The ultimate thing-like entities not only failed to accommodate the
things of our actual experience,
but have turned out not to be thing-like at all.
Although the atoms of modern chemistry and physics are moderately thing-like,
subatomic entities are not.
We do not obtain predictions borne out by observation if we count
as different the case of this electron being here and that there
and the case of that being here and this there.
Instead of thinking of the word `electron' being a substantive
referring to a substantial, identifiable thing,
we do better to think of it as an adjective,
with some sense of `negatively charged hereabouts'.
We do not feel tempted to distinguish two pictures,
one of which is red here and red there,
and the other of which is red there and red here;
the qualities referred to by adjectives lack haecceitas,
this-i-ness, and are real only in so far as they are instantiated.

We are forced to deny this-i-ness to electrons and other sub-atomic entities
in order to accommodate empirical observations,
but it is not just a brute fact, but rather the reflection of the
probabilistic structure of quantum mechanics.
The loss of determinateness in our ultimate ontology is the
concomitant of our abandoning determinism in our basic scheme of explanation.
Probabilities attach naturally not to specific singular propositions,
but to general propositional functions, or,
as Colin Howson puts it,
3
generic events, or, in Donald Gillies' terminology,
4
repeatable situations.
Although you can intelligibly ask what the probability is of my
dying in the next twelve months, the answer is nearly always only an estimate,
extrapolated from the probabilities of Englishmen, males,
oldie academics, non-smokers, non-diabetics, and other relevant general types,
not dying within the subsequent year.
Calculations of probabilities depend on the law of large numbers,
assumptions of equiprobability, or Bayes' Theorem,
which all ascribe probabilities to propositional functions dealing
with general properties rather than to singular propositions
asserting ultimate particularities.
If we accept the probabilistic view of the world,
we can no longer picture the universe as made up of particular
thing-like entities that Newton could have asked Adam to name,
but as a featured something, whose underlying propensities could
be characterized in quantum-mechanical terms, and whose features
calculated up to a point, and found to be borne out in experience.

The loss of particularity legitimises a paradigm shift in our canon of explanation.
In his Presidential Address, Professor Redhead noted the shift
from a Nineteenth Century ideal, in which we could deduce
the occurrence of events granted a unified theory
together with certain boundary conditions,
to a Twentieth Century schema,
which, although less demanding, in as much as it is not deterministic,
is more demanding, in that it seeks to explain the boundary
conditions too.
5
Outside physics that has always been the case---and often within physics too.
It is one of the chief objections to the Hempelian canon,
an objection expressed by many of those present here
tonight---Nancy Cartwright, John Worrall, Peter Lipton---that it
fails to accommodate the types of explanation scientists actually
put forward.
6
It depends on the science concerned what patterns of law-like association,
to use a phrase of David Papineau's, count as causes.
7
Different sciences count different patterns of law-like associations
as causes because they ask different questions and therefore need
to have different answers explaining differently with different becauses.
The fact that different sciences ask different questions is of crucial importance.
Once we distinguish questions from answers,
we can resolve ancient quarrels between different
disciplines.
8
The biologists have long felt threatened by reductionism, and felt
that there was something amiss with the claim that it was all in
the Schrödinger equation, or as Francis Crick put it,
``the ultimate aim of the modern movement in biology is in fact to
explain all biology in terms of physics and chemistry''.
9
But their claim that there was something else,
not in the realm understood by physicists, smacked of vitalism,
and was rejected out of hand by all practising physicists.
Vitalism made out that answers were in principle unavailable,
whereas what is really at issue is not a shortage of answers but
an abundance of questions.
It was not a case of biologists asking straightforward physicists'
questions and claiming to get non-physicists' answers,
but of their asking non-physicists' questions,
to which the physicists' answers were germane, but could not,
in the nature of the enquiry,
constitute an exhaustive answer to what was being asked.
Biologists differ from physicists in what they are interested in---no
hint of vitalism in pointing out that the life sciences investigate
the phenomenon of life---and in pursuing their enquiries pick on
features which are significant according to their canons of interest, not the physicists'.
What is at issue is not whether there is some physical causal
process of which the physicists know nothing, but whether there
are principles of classification outside the purview of physics.
It is a question of concepts rather than causality.

My favourite, excessively simpliste example is that of the
series of bagatelle balls running down through a set of evenly
spaced pins and being collected in separate slots at the bottom:
we cannot predict into which slot any particular ball will go,
but we can say that after a fair number have run down
through the pins, the number of balls in each slot will
approximate to a Gaussian distribution.
There is nothing vitalist about a Gaussian distribution,
but it is a probabilistic concept, unknown to Newtonian mechanics.
In order to recognise it, we have to move from strict
corpuscularian individualism to a set, an ensemble, or a
Kollectiv of similar instances, and consider the properties of the whole lot.
More professionally, all the insights of thermodynamics
depend on not following through the position and momentum
of each molecule, but viewing the ensemble in a more
coarse-grained way, and considering only the mean
momentum of those molecules impinging on a wall,
or the mean kinetic energy of all the molecules in the vessel.
Equally the chemist and the biologist are not concerned
with the life histories of any particular atoms or
molecules, and reckon one hydrogen ion as good as another,
and one molecule of oxygen absorbed in the lungs of a blackbird as good as another.
10
The chemist is concerned with the reaction as a whole,
the biologist with the organism in relation to its
environment and other members of its species.
A biologist is not interested in the precise accounting
for the exact position and momentum of every atom,
even if that were feasible.
Such a wealth of information would only be noise,
drowning the signal he was anxious to discern, namely the
activities and functioning of organisms, and their
interactions with one another and with their ecological
environment.
It is the song of Mr Blackbird as he tries to attract the
attention of Mrs Blackbird that concerns the ethologist.
He is not concerned with exactly which oxygen molecules
are in the blackbird's lungs or blood stream, but in the
notes that he trills as dawn breaks, and their
significance for his potential mate. If he were
presented with a complete Laplacian picture, his first
task would be to try and discern the relevant patterns of
interacting carbon, oxygen, hydrogen and nitrogen atoms
that constituted continuing organisms, and to pick out
the wood from the trees. In this change of focus the
precise detail becomes irrelevant. He is not, in
Professor Watkins' terminology, a methodological
individualist. What interests him is not the life
history of particular molecules of oxygen, but the metabolic state of the organism, which will be the same in either case. Different disciplines, because they concentrate on different questions, abstract from irrelevant detail, in order to adduce the information that is relevant to their concerns.

In practice scientists have long recognised that in order to see the
wood they must often turn their attention away from the trees. But
whereas that shift was to be defended simply as a matter of choice
on their part, now it is legitimised by our new understanding of
logical status of the boundary conditions we are interested in. If
our ultimate theory of everything can talk only in general terms, and
cannot assign positions and velocities to particular atoms, it follows
that it is no criticism of other theories that they can talk only in
general terms too. Hitherto there has been a sense of information
being thrown away, information which was there and ultimately
important, so that we were, in some profound way, being given less
than the whole truth. There was a Laplacian Theory of Everything
which was in principle knowable and in principle held the key to all
ologies. Every other discipline was only a partial apprehension of
ultimate truth, useful perhaps because more accessible for our
imperfect minds, but conveying only imperfect information none the
less. Just as we rely on journalists to reduce the welter of
information about the Balkans or South America to manageable size, so
chemists and biologists seemed to select and distil from total truth to
tell us things in a form we were capable of taking in. Compared with
the high priests of total truth, they were mere popularisers. I may
discern Gaussian patterns in long runs of bagatelle balls, but they
are patterns only in the eye of an ill-informed beholder: better
informed, I should see why each ball went into the slot that it did,
and be aware of the occasions when a non-Gaussian distribution
emerged. My Gaussian discernment would seem a rough and ready
approximation, like describing France as hexagonal, which is fair
enough for some purposes, but falls far short of being fully true.
Even though the things we pick on as worthy of note and in need of
explanation---the shape of the Gaussian curve, the significance of
bird-song---lie outside the compass of the limited concepts and
explanation of a Theory of Everything, the possession of perfect
information trumps curiosity.

The case is altered if there is no fully particularised ultimate
reality, and no complete theory of it. We cannot claim that ultimately
there are trees which exist in their own right, whereas the woods are
only convenient shorthand indications of there being trees there: we
cannot trump the different, admittedly partial, explanations put
forward by different disciplines by a paradigm one that claims to be
complete, nor can we suppose that there is some bottom line that
establishes a final reckoning to which all other explanations must be
held accountable. All natural sciences concern themselves with
general features of the universe, and there is no reason to
discountenance any science because it selects some general features
rather than others. Questions about boundary conditions cannot,
then, be faulted on grounds of their being general, and not
ultimately particular. The answers, too, are to be assessed
differently, once the mirage of a complete Laplacian explanation is
dispelled. Not only is it irrelevant to the ethologist's purposes,
which particular mate the blackbird seeks to attract, or which oxygen
molecules are in the blackbird's lungs or blood stream, it is, in its
precise detail, causally irrelevant too. The blackbird's song is not
addressed to a particular Mrs Blackbird in all her individuality, but
to potential Mrs Blackbirds in general, and if one mate proves hard
to win, another will do. Much more so at lower levels of existence: if
one worm escapes the early bird, another will be equally succulent; if
one molecule of oxygen is not absorbed by his haemoglobin, another
will. Explanations are inherently universalisable, and if the physical
universe is one of qualitatively identical features that cannot, even in
principle, be numerically distinguished, then the explanations offered
by other disciplines are ones that cannot, even in principle, be
improved upon by a fuller physical explanation. Indistinguishability
and indeterminism imply a looseness of fit on the part of physical
explanation which take away its Procrustean character. The new
world-view makes room for there being different sciences which are
autonomous without invoking any mysterious causal powers beyond
the reach of physical investigation.

The autonomy I am arguing for is, in the words of Bechner,
11
theory autonomy rather than a process autonomy: we use new
concepts to ask new questions, rather than find that old questions
have suddenly acquired surprising new answers. But this distinction
between questions and answers offers a solution to the problem of
reductionism only if there is some further fundamental difference
between the concepts involved in framing the questions asked by
different sciences. Otherwise, they might still be vulnerable to a
take-over bid on the part of physics. A reductionist programme
whereby every concept of chemistry and physics is exhaustively
defined in terms of physical concepts alone might still be mounted.
Thus far I have only cited examples---Gaussian curves, temperature,
blackbird song---where reductive analysis seems out of the question.
But the unavailablity of reductive analyses is much wider than that.
Tony Dale bowled me out recently, when I had overlooked the fact
that the concept of a finite number cannot be expressed in first-order logic. The very concept of a set, and more generally of a
relational structure, is a holistic one. But rather than multiply
examples, let me cite an in-principle argument. Tarski's theorem
shows that the concept of truth cannot be defined within a logistic
calculus: roughly, although we can teach a computer many tricks, we
cannot program it to use the term `true' in just the way we do. It
therefore seems reasonable to hold that other concepts, too, are
irreducible, and the failure of the reductionist programme is due not
to some mysterious forms of causality but to our endless capacity to
form new concepts and in terms of them to ask new questions and
seek new types of explanation.

The new world-view we are being forced to adopt not only permits us
to concern ourselves, qua scientists, with general features,
but impels us to do so. Even the corpuscularian philosophy gave
somewhat short shrift to the things of ordinary experience. Most
configurations of atoms were transitory. Even rocks were subject to
the attrition of time, and the mountains, far from being eternal, were
being eroded by the wind and the rain. Processes could in principle
withstand the ravages of time, and at first glance Liouville's theorem
seemed to suggest that point-particles whose initial conditions were
close to one another would end up close still. But although, indeed,
there was a one-one correlation between initial and final conditions,
the correlation was much less stable than at first sight appeared.
True, the volume in phase-space remains constant, but its shape does
not, and may become spreadeagled with the elapse of time, so that
the very smallest difference in initial conditions can lead to a wide
difference in outcome. Poincaré pointed out the logic of the roulette
wheel,
12
and we now regularly hear of the damage done by
irresponsible butterflies on the other side of the universe destroying
the reliability of met office forecasts. No longer can Newton number
the ultimate things among the
(kumaton anerithmon gelasma),
the innumerable laughter of quantum waves, but if he wants atoms,
must raise his sights to those stable solutions of the Schrödinger
time-independent equation, which one way or another, will be
realised. And although some solid objects are likely to remain
substantially the same over time, most collocations of atoms are
evanescent. If we seek stability amid the flux of molecular movement,
we are likely to find it at a higher level of generality where chaos
theory can indicate the recurrence of relatively stable patterns. In
the Heraclitean swirl eddies may last long enough to be identified.
Flames are processes, but possess the thingly property of subsisting
and sometimes of being identified and individuated. So if we want
permanence, we shall be led to focus on certain general features,
certain types of boundary condition, which can persist over
reasonable stretches of time. Just as chemists look to the
time-independent Schrödinger equation to show them what stable
atomic configurations there are, and would like to be able to work out in
detail what molecules are stable too, so at a much higher level,
biologists take note of organisms and species of organisms, which are
the basic things of their discipline. Organisms are homeostatic,
self-perpetuating and self-replicating. They are processes, like
flames, but longer lasting and with greater adaptability in the face of
adventitious change. They react to adverse changes in the
environment so as to keep some variables the same, which together
constitute the same organism that survives over time in the face of
alterations in the environment. There is thus an essential difference
between organism and environment which differentiates all the life
sciences from the physical ones. Thinghood has become modal as well
as diachronic. It is not enough to continue to be the same over time:
organisms need to be able to change in some respects in order to
remain the same in others, more important. Even if I were to alter
the environment by watering the garden, moving the bird table,
replacing the coconut with peanuts, the flora and fauna, though
responding in various ways to the altered situation, would mostly
persist as the self-same organisms as if I make no alterations. This
invariance under a limited range of altered circumstance is more like
the invariance of operation of natural laws than the continuance of
atomic matter, but goes further; laws of nature would operate even if
initial conditions were different, but do not characteristically alter
their mode of operation so as to restore some antecedent condition,
whereas biological organisms typically do, provided the alteration of
initial conditions is not too drastic.

Homeostasis is a familiar concept in science---but logically a
treacherous one. A homeostatic system tends to maintain the same
state, and sameness can easily shift without our noticing it. The
simple negative feedback of a flame or an eddy or a thunderstorm
results in the process not being interrupted by every adventitious
alteration of circumstance, but the persistence is short-lived none the
less. Living organisms last longer, and are better able to withstand
the attrition of time, because they react to counter the effect of a
wider variety of circumstances. The requirement of persistence
alters what we count as the substance that persists, and per contra
as the concept of substance develops, so also does our idea of what
counts as survival, and more generally what goals the substance
seeks to secure and maintain. We begin to recognise as important
explanatory schemata not only the survival of the organism, but the
survival of the species, and now, even, the survival of the biosphere.
And we begin to see not only the individual's maximising its own
advantage as a rational goal, but the value of co-operative action, if
we are to escape from the Prisoners' Dilemma and not be driven by
individual selfishness into collective sub-optimality. Beyond that, I
find it difficult to peer, but still hope dimly to discern the lineaments
of what, if I may borrow a suggestive phrase from Nicholas Maxwell,
13
we might describe as an aim-oriented rationality.

The concept of homeostasis is borrowed from control
engineering.
It leads on naturally into information theory, and
information theory provides the key concepts for understanding
genetics. As self-perpetuation gives rise to self-replication, there is
a greater need for the exact specification of the self, and the
chromosome needs to be understood not only biochemically as a
complicated molecule of DNA, but as a genetic code specifying what
the new organism is to be like. Once again, the change of emphasis
from the particular physical configuration to the general boundary
condition, and the looseness of fit between the probabilistic
explanations of the underlying physics and the quite different
explanations of the emergent discipline allow us to accommodate the
new insights without falling into obscurantist
obfuscation.
14
Homeostasis also implies sensitivity. If an organism is to be
independent of its environment, it must respond to it so as to
counteract the changes which the changes in the environment would
otherwise bring about within the organism itself: if I am to maintain a
constant body temperature, I must sweat when it is hot outside and
shiver when it is cold. Even plants must respond to light and to the
earth's gravitational field. The greater the independence and the
more marked the distinction between the self and the non-self, the
greater the awareness the self needs to have of the non-self, and the
more it needs to register, so as to be able to offset, untoward
changes in the world around it. We are still in the dark as to what
exactly consciousness is or how it evolved, but can see in outline
why it is needed. A windowless monad cannot survive the changes
and chances of this fleeting life---sensitivity to clouds on the
horizon no bigger than a man's hand is the price of not being
destroyed by unanticipated storms.

My interest lies in the end of this line of development. We can give
a general characterization of what it is for a system to be able to
represent within itself some other system, and so can think of
organisms in terms not of biochemistry or evolutionary biology but of
information theory and formal logic. And from this point of view we
can consider not only consciousness but self-consciousness, and a
system that can represent within itself not just some other system
but itself as well. There are a whole series of self-reflexive
arguments. Popper, a former President of our Society, has devoted
much energy to arguing from them to an open universe; in particular,
he argues from the impossibility of self-prediction. MacKay argues
similarly---other people may predict what I am going to do, but I
cannot.
15
Many people, Haldane,
Joseph, Malcolm, Mascall, Popper, Price, Wick and others, have been
concerned about rationality, and have argued that if determinism or
materialism were true, we could not be rationally convinced of
it.
16
Reductive metaphysics, which reduces rationality to something
else---the movement of physical particles, for example---cannot leave
room for the rational arguments which alone could establish its truth.
I myself found these arguments intriguing, and indeed, compelling,
but extraordinarily difficult to formulate in a cast-iron way.
Eventually I came up with an argument based on Gödel's theorem,
which is indeed a version of these arguments, and is intended to
show in one swoop the failure of any reductionist programme as
regards reason. I have received much stick for using Gödel's
theorem to show that the mind is not a Turing machine, but I am
quite impenitent on that score, and believe that the argument goes
much further, and shows not only the impossibility of reducing
reason to the mere following of rules, but the essential creativity of
reason. We can never formalise reason completely or tie it down to
any set of canonical forms, for we can always step outside and view
all that has been thus far settled from a fresh standpoint. In
particular we can find fresh features that seem significant, and seek
fresh sorts of explanation of them. It does, I believe, establish the
essential openness of the universe, granted only that there is at
least one rational agent. If there be rational agents, since we are
rational agents, it follows that the course of events in the universe
cannot be reduced to a system of things evolving according to a
determinate algorithm, but that there are always new opportunities
and further possible exercises of rationality.

The interplay between things and explanations is illuminating.
Instead of starting with things, we are able to identify things only at
higher levels of organization, and the higher we go the more thingly
properties we find. Atoms have stability (usually), but are
qualitatively identical with many others. Organisms have more
individuality, and are less commonly clones, but still view their
environment if not in terms of chemical similarity nevertheless in
terms of fungibility, readily replacing one food supply by another.
Nor is it only the environment that organisms regard fungibly:
although some birds are faithfully monogamous, many are not, and if
one Mrs Blackbird fails to respond to the musical blandishments of
her would-be mate, another will serve his reproductive purposes just
as well. Human love likewise is not uniformly faithful to the
individual ideal, but with human beings we can see this as a
derogation from humanity, and can construct a coherent concept of
unique individuality, according to which this person is irreducibly
himself, and essentially different from anybody else.
17
Our idea of
thinghood leads us from the utterly simple and essentially similar
atoms of the corpuscularians to infinitely complex and unique
persons, each necessarily different from every other.

The different ideals of thinghood support different paradigms
of explanation. Since different sorts of feature characterize things at
different levels, and the features that characterize at the higher
levels cannot be completely defined in terms of those that play a part
in lower-level explanations, the higher-level explanations cannot be
reduced to lower-level ones. As we have seen, a Gaussian curve
cannot be defined in terms of a Laplacian explanation, for it
essentially involves the notion of an ensemble or Kollectiv.
Higher-level systems are not derivable from some fundamental system, but
are, instead, autonomous.
We cannot predict the exact position or velocity of a sub-atomic entity,
but by means of the time-independent Schrödinger equation
we can say what properties a hydrogen atom would have if it existed,
and we can have good reason for supposing that many such atoms
will exist, since they are stable configurations of quantum-mechanical
systems. The explanations sought by a chemist are in terms of
energy levels and the valency bonds they generate: those sought by
the biologist are in terms of the maintenance of life and the
continuation of the species. And as these explanations differ, so also
do the things they are explanations about. Explanations influence
what is to count as a thing, and ideas of what it truly is to be a
thing influence what questions we ask, and what explanations we seek
to discover.
18
We can see this, if we like, as a form of emergent
evolutionary development: new levels of being evolve from lower,
chemical elements from the flux after the Big Bang, molecules,
organisms, consciousness, and self-consciousness, in the fullness of
time; but we can also see it in terms of a hierarchy of Platonic forms
and explanations, each going beyond the limits of its predecessors,
and at the higher levels reaching out to ever new kinds of creative rationality.

To summarise, then. The new scientific world-view differs from
traditional corpuscularianism in not postulating some ultimate
thing-like entities whose motions determine completely the state of
the world not only at that time but at all subsequent ones too.
Instead of there being particular point-particles, there are only
general features, and instead of a rigid determinist law, there are
only probabilities, which are, indeed, enough to enable us to make
reliable predictions about many aspects of the world, but do not
foreclose the possibility of other types of explanation being the best
available. Other types of explanation are answers to other types of
questions, and it is because we ask different questions that the
different sciences are different. These different questions pick on
different general features, often different types of boundary
condition; and once we acknowledge that there is no metaphysical
reason to reduce the generic characterization of boundary conditions
typical of other sciences to the paradigm physical terms of Laplacian
corpuscularianism, we can accept these other sciences as sciences in
their own right, since, metaphysics apart, we have good reason to
resist reductionism as applied to questions rather than answers.

The abolition of ultimate things thus opens the way to our
acknowledging the autonomy of the various sciences. At the same
time, the notion of a thing leads us to pick out various types of
boundary condition as instantiating, to a greater and greater degree,
certain characteristic features of being a thing---permanence,
stability, ability to survive adventitious alterations in the
environment, and the like. As we follow these through, we find a
natural hierarchy of the sciences in which we ask questions about
more and more complicated entities, possessing more and more thing-like perfections. Things have gone up market. By an almost
Hegelian dialectic our notion of a thing becomes transmuted into that
of a substance, and in so far as we remain pluralists at all, we move
from the minimal qualitatively identical, though numerically distinct,
atoms of the corpuscularians to the infinitely complex, though
windowed, monads of a latter-day Leibniz. Whether Lucretius would
have been pleased at this outcome of the complex interplay between
ontological intimations of existence and rationalist requirements of
explicability, I do not know. But he could hardly complain at my
taking this as my theme, here at an address to the British Society
for the Philosophy of Science taking place in the London School of
Economics, whose motto is taken from Virgil's description of him, and
also expresses the common sentiment of all our members,

Felix qui potuit rerum cognoscere causas

Happy he who understands the explanations of things

To return from footnote to text, click on footnote number

1.
Michael Redhead, ``A Philosopher Looks at Quantum Field Theory'', in
Harvey Brown and Rom Harré, eds., Philosophical Foundations of Quantum Mechanics, Oxford, 1988, p.10.
2.
Robin Le Poidevin, Change, Cause and Contradiction, London, 1991, esp. ch.8.
3.
C.A.Howson and P.Urbach,
Scientific Reasoning: the Bayesian Approach,
La Salle, Illinois, USA, 1989, p.19.
4.
D.A.Gillies,
Objective Probability, Cambridge, 1973, esp. ch.5.
5.
Reprinted in S.French and H.Kamminga, eds.,
Correspondence, Invariance and Heuristics,
(Kluwer Academic Publishers, Holland), 1993, p. 329.
6.
Nancy Cartwright, How the Laws of Physics Lie, Oxford, 1983, ch.2, esp. pp.44-46. Peter Lipton, Inference to the Best Explanation, London, 1991, esp. ch.3; John Worrall, ``The Value of a Fixed Methodology'', British Journal for the Philosophy of Science, 39, 1988.
7.
David
Papineau, British Journal for the Philosophy of Science, 47, 1991, p.399.
8.
I owe this point to H.C.Longuet-Higgins,
The Nature of Mind, Edinburgh, 1972, ch.2, pp.16-21, esp. p.19;
reprinted in H.C.Longuet-Higgins, Mental Processes,
Cambridge, Mass., 1987, ch.2, pp.13-18, esp.p.16.
I am also particularly indebted to
C.F.A.Pantin, The Relations
between the Sciences, Cambridge, 1968; and to A.R.Peacocke, God
and the New Biology, London, 1986, and Theology for a
Scientific Age, Oxford, 1990. Michael Polanyi emphasized the
importance of boundary conditions and their relevance to the
different sorts of explanation sought by different disciplines.
In his ``Tacit Knowing'', Reviews of Modern Physics,
October, 1962, pp.257-259, he cites the example of a steam engine,
which although entirely subject to the laws of chemistry and
physics, cannot be explained in terms of those disciplines alone,
but must be explained in terms of the function it is capable, in
view of its construction, perform.
What is interesting about the steam engine is not the laws of
chemistry and physics, but the boundary conditions, which in
view of those laws, make it capable of transforming heat into
mechanical energy; it is the province of engineering science, not
physics. The example of the steam engine is illuminating in that no
question of vitalism arises. See also, Michael Polanyi, ``Life
Transcending Physics and Chemistry'', Chemical and Engineering News, August 21, 1067, pp.54-66;
and ``Life's Irreducible Structure'', Science, 160, 1968,
pp.1308-1312.
9.
F.H.C.Crick,
Of Molecules and Man,
University of Washington Press,
Seattle and London, 1966, p.10.
10.
That the biologist is primarily concerned with boundary conditions of a special type is pointed out by Bernd-Olaf Küppers,
Information and the Origin of Life,
M.I.T. Press, Cambridge, Mass, U.S.A., 1990, p.163.
11.
Compare the distinction drawn by M.Bechner between theory autonomy and process autonomy in his ``Reduction, Hierarchies and Organicism'' in F.J.Ayala and T.Dozbhanski,
Studies in the Philosophy of Biology: Reduction and Related Problems,
London, 1974, p.170; cited by A.R.Peacocke,
God and the New Biology, London, 1986, p.9.
12.
Henri Poincaré, Science and Method, tr. F.Maitland,
London, 1914, p.68.
13.
Nicholas Maxwell, From Knowledge to Wisdom, Oxford, 1984, esp. ch.4.
14.
Nicholas Maxwell, From Knowledge to
Wisdom, Oxford, 1984, esp. ch.4.
15.
D.M.MacKay, ``On the Logical Indeterminacy of a Free
Choice'', Mind, LXIX, 1960, pp.31-40.
16.
See K.R.Popper, The Open Universe, ed. W.W.Bartley,
III, London, 1982, ch.III, $$ 23,24. Popper traces the argument back
to Descartes and St Augustine. A further list is given in J.R.Lucas,
The Freedom of the Will, Oxford, 1970, p.174. Further arguments and fuller references may be found in Behavioral Sciences, 1990, 13, 4.
17.
I argue this in my ``A Mind of One's Own'',
Philosophy, October, 1993.
18.
Compare A.R. Peacocke, Theology for a
Scientific Age, Oxford, 1990, p.41: Because of widely pervasive
reductionist presuppositions, there has been a tendency to regard
the level of atoms and molecules as alone `real'. However, there are
good grounds for not affirming any special priority to the physical
and chemical levels of description and for believing that what is real
is what the various levels of description actually refer to. There is
no sense in which subatomic particles are to be graded as `more real'
than, say, a bacterial cell a human person or a social fact. Each
level has to be regarded as a slice thorough the totality of reality, in
the sense that we have to take account of its mode of operation at
that level.
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